Grav\Plugin\Admin\Gpm::_downloadSelfupgrade PHP Method

    private static function _downloadSelfupgrade(array $package, $tmp)
    {
        $output = Response::get($package['download'], []);
        Folder::mkdir($tmp);
        file_put_contents($tmp . DS . $package['name'], $output);
        return $tmp . DS . $package['name'];
    }